This application is based on and claim priority under 35 U.S.C. xc2xa7 119 with respect to Japanese Application No. 2001-050513 filed on Feb. 26, 2001, the entire content of which is incorporated herein by reference.
This invention generally relates to a vehicle door opening and closing mechanism. More particularly, the present invention pertains to a vehicle door opening-closing device which includes a latch mechanism for maintaining a vehicle door at a half closed condition and at a fully closed condition engaged with a striker, an operation mechanism for fully closing the vehicle door and for releasing the closed door condition through operation of the latch mechanism, and an actuator for actuating the operation mechanism.
A known vehicle door opening-closing device is disclosed in Japanese Patent Laid-Open Publication No. S62-101782. This known vehicle door opening-closing device includes two rods connected to two arms having approximately the same length and rotatable about a common rotation center with a rotation plate (i.e., an operation member). The rods are operated by the rotation of the rotation plate driven in both a normal direction and a reverse direction with one motor to thus operate a latch forming a part of the door lock mechanism.
When the motor is operated in the normal direction, one of the rods is operated to prepare for disengaging the striker of the vehicle door from the latch. In this condition, the vehicle door can be freely opened. When the motor is driven in the reverse direction, the other rod is operated to force the latch to rotate to a fully latched condition. Under the fully latched condition, the striker is engaged with the latch to fully close the vehicle door.
During closing operation, it is necessary to close the vehicle door against the compression reaction force of a weather strip provided between the vehicle door and a vehicle body in order to fully close the vehicle door. Thus, the latch requires a relatively large force to pull in the striker.
In the known vehicle door opening-closing device described above, to ensure a sufficiently large force, the reduction gear ratio between the motor and the rotation plate is increased to increase the torque on the rotation plate side. The greater the torque amount is increased, the smaller the moving amount of the rods per unit of rotational angle of the motor (i.e., the slower the moving speed of the rods becomes) and the greater the force of the latch for pulling in the striker.
Because the two arms in the aforementioned known vehicle door opening-closing device have approximately the same predetermined length, the door lock mechanism is operated with the same power in both the normal drive operation of the motor and the reverse drive operation of the motor. That is, the door lock mechanism is operated with a slow rod moving speed that is the same when fully closing the vehicle door as it is when it is operating to disengage the latch and the striker, notwithstanding that when the door lock mechanism is operated to release the engagement between the latch and the striker it is not necessary to operate against the compression reaction force of the weather strip. This lengthens the time from when the operation for opening the fully closed vehicle door is started until the time when the vehicle door is actually opened. This operation may be viewed by users as undesirable and annoying.
A need thus exists for a vehicle door opening-closing device which has a constant driving force of the actuator and the driving speed both when fully closing the vehicle door from the half closed condition and when releasing the fully closed condition and shortens the time for releasing the fully closed condition.
According to one aspect, a vehicle door opening-closing device includes a latch mechanism engageable with a striker for effecting a half closed condition of the vehicle door and a fully closed condition of the vehicle door, an operation mechanism operatively engageable with the latch mechanism at a point of force application to operate the latch mechanism during a closing operation from the half closed condition to the fully closed condition and during an opening operation to release the fully closed condition of the vehicle door, and an actuator for actuating the operation mechanism. The operation mechanism operates the latch mechanism with a smaller force and faster moving speed of the point of force application during the opening operation compared to during the closing operation under a driving force and a driving speed of the actuator that are approximately the same during release of the fully closed condition of the vehicle door and during movement of the vehicle door from the half closed condition to the fully closed condition.
According to another aspect, a vehicle door opening-closing device includes a latch mechanism engageable with a striker for effecting a half closed condition of the vehicle door and a fully closed condition of the vehicle door, a movable opening lever having a fulcrum and engageable with the latch mechanism at a first point of force application to operate the latch mechanism during an opening operation to release the fully closed condition of the vehicle door, and a movable closing lever having a fulcrum and engageable with the latch mechanism at a second point of force application to operate the latch mechanism during a closing operation to move the vehicle door from the half closed condition to the fully closed condition. The distance between the fulcrum of the opening lever and the first point of force application is greater than a distance between the fulcrum of the closing lever and the second point of force application. A motor produces an output to move the opening lever into engagement with the latch mechanism and to move the closing lever into engagement with the latch mechanism. The motor is operating under a driving force and a driving speed during release operation of the fully closed condition of the vehicle door that is the same as the driving force and the driving speed under which the motor is operated during movement of the vehicle door from the half closed condition to the fully closed condition.
In accordance with another aspect of the invention, a vehicle door opening-closing device includes a latch mechanism engageable with a striker and positionable in a half latched condition and a fully latched condition, a motor, an operation member operatively associated with the motor to move under driving operation of the motor, a movable opening lever having a fulcrum and a movable closing lever also having a fulcrum. The opening lever is adapted to be contacted by the operation member at a first contacting point to move the opening lever into contact with the latch mechanism at a first point of force application of the opening lever to operate the latch mechanism and effect release of the fully latched condition of the latch mechanism. The movable closing lever is adapted to be contacted by the operation member at a second contacting point to move the closing lever into contact with the latch mechanism at a second point of force application of the closing lever to operate the latch mechanism from the half latched condition to the fully latched condition. The opening lever possesses a lever ratio defined as a ratio of a distance between the fulcrum of the opening lever and the first contacting point relative to a distance between the fulcrum of the opening lever and the first point of force application. The closing lever possesses a lever ratio defined as a ratio of a distance between the fulcrum of the closing lever and the second contacting point relative to a distance between the fulcrum of the closing lever and the second point of force application. The lever ratio of the opening lever is less than the lever ratio of the closing lever.